You can do it as you've suggested and make a beautiful port/tarragon reduction. It lends such a beautiful rich flavor to the foie, and if you make just a touch of infused tarragon 0il, a drizzle of jus and oil is a great "bottom" for the foie.Otherwise, we like it stuffed into fig halves or dates, and baking, serving with a really light scatter of goat cheese or bleu cheese.